[Python] ModInverse code snippet

ModInverse code snippet: (depends on ExtendedGcd())

def ModInverse(a, m):
  """
  Modular multiplicative inverse algorithm.

  Computes modular multiplicative inverse of an integer a is an integer x such
  that the product ax is congruent to 1 with respect to the modulus m.

  Args:
    a: An integer.
    m: An integer representing modulus.

  Returns:
    An integer x satisfying ax = 1 (mod m). Otherwise throw an exception if
    there is no such integer x.
  """
  g, x, y = ExtendedGcd(a, m)
  if g != 1:
    raise Exception('modular inverse does not exist')
  return x % m